Adjuvant-free parenterally injectable vaccine platform that harnesses previously induced IgG as an antigen delivery carrier.

Biochem Biophys Res Commun

Laboratory of Nano-Design for Innovative Drug Development, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan; Vaccine Creation Group, BIKEN Innovative Vaccine Research Alliance Laboratories, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan; The Research Foundation for Microbial Diseases of Osaka University, Osaka, Japan; Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan; Center for Advanced Modalities and DDS, Osaka University, Osaka, Japan; Vaccine Creation Group, BIKEN Innovative Vaccine Research Alliance Laboratories, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Osaka, Japan; Global Center for Medical Engineering and Informatics, Osaka University, Osaka, Japan. Electronic address:

Published: June 2024

Subunit vaccines are among the most useful vaccine modalities; however, their low immunogenicity necessitates the addition of adjuvants. Although adjuvants improve immune responses induced by vaccines, they often cause adverse reactions. To address this, we developed an adjuvant-free subunit vaccine platform that uses pre-existing antibodies generated from past infections or vaccinations as carriers for the delivery of vaccine antigens. Although we have confirmed the usefulness of this platform for nasal vaccines, its suitability as a parenterally injectable vaccine remains uncertain. Here, we verified the potential of our vaccine platform to harness pre-existing immunity for parenterally injectable vaccines. We generated RBD-HA by combining the receptor binding domain (RBD) derived from SARS-CoV-2 as a vaccine antigen with hemagglutinin (HA) sourced from influenza viruses to serve as the carrier protein. We revealed that subcutaneous vaccination with RBD-HA effectively triggered strong RBD-specific IgG responses in mice previously infected with the influenza A virus, even in the absence of adjuvants, and conferred protection to mice against SARS-CoV-2 upon challenge. Furthermore, we revealed that vaccination with RBD-HA did not induce an inflammatory response, such as inflammatory cytokine production, swelling, and recruitment of inflammatory immune cells, whereas conventional vaccines combined with adjuvants induced these adverse reactions. In addition, we demonstrated the remarkable versatility of this platform using a vaccine antigen derived from Streptococcus pneumoniae. These findings indicate the potential of this adjuvant-free vaccine platform to enhance the efficacy of parenterally injectable subunit vaccines and reduce adverse reactions.

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Source
http://dx.doi.org/10.1016/j.bbrc.2024.149919DOI Listing

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